Saw-tooth current generator



Oct. 27, 1953 J. HAANTJES ETAL SAW TOOTH CURRENT GENERATOR Filed Dec. 1, 1950 2 Sheets-Sheet i #503 r INVENTORS JOHAN HAANTJES JOSUE J. P. VALETON BERNARDUS W.V.|.

SCHENAU @W AGENT Oct. 27, 1953 J. HAANTJES ET AL 2,657,333

SAW TOOTH CURRENT GENERATOR Filed Dec. 1,1950 z'sh-eets-sneei 2 I 5s $4 f-ss HI- E as 5 E 65? W ii 5.9

INVENTORS JOHAN HAANTJES JOSUE J.P VALETON BERNARDUS W.V.|. SCHENAU AGENT Patented Get. 27, 1953 UNi'l'ED STATES PATENT OFFICE SAW-TOOTH CURRENT GENERATOR Goran as trustee Application December 1, 1950, Serial No. 198,576 In the Netherlands December 31, 1949 14 Claims.

The present invention relates to a circuitarrangement for producing a saw tooth current in a deflection coil of a cathode ray tube, and more particularly to such a circuit-arrangement wherein the voltage pulse occurring across the circuit during the fiy-back of the saw tooth current is rectified to produce a direct voltage for the supply of the cathode ray tube.

Such circuit-arrangements, which may conveniently be used in television receivers in which the high voltage for the cathode ray tube is de- The principal object of the present invention is to provide a circuit-arrangement in which;v

these limitations are obviated.

More particularly, it is an object of the invention to provide a circuit-arrangement of the above type wherein the direct voltage for the supply of cathode ray tubes is substantially independent of load variations.

Another object of the invention is to provide a circuit-arrangement of the above type wherein a direct voltage for the supply of the cathode ray tube is substantially independent of the load variations and wherein the linearity of the saw tooth deflection current is substantially unaffected by load variations.

Further objects of the invention will appear from the following description.

According to the invention, at a time during the fiy-back of the saw tooth current but prior to the time at which the rectifier is cut oil, the voltage pulse is damped by a load which varies in a sense opposite to the damping variations? produced by variations in the cathode ray tube load.

The circuit-arrangement according to the invention is based on recognition of the fact that,

during the stroke of the saw tooth current, energy is accumulated in the electromagnetic field of the deflection coil. During the fly-back of the saw tooth current, this coil, which is included in the output circuit of a discharge tube either directly or through a transformer, becomes damped out in its natural frequency, very high voltages being liable to occur across the coil of the said transformer, if the capacities in parallel with the coil or the transformer are low. With the use of one or more rectifiers this high voltage is rectified and, if necessary, multiplied.

After half a period the oscillation is frequently extinguished and the energy then left in the coil is usefully employed for the deflection circuit, which may be effected, for example, if an efficiency diode or a booster diode is included in this circuit. The damping of the oscillation produced now varies with the load of the rectifying circuit.

If this load is to be prevented from affecting the saw tooth deflection current produced, care must be taken to ensure that, after half the period of the oscillation, the same quantity of energy invariably is left in the deflection coil or the transformer winding.

According to the invention, this can be achieved by providing an additional damping which varies in an opposite sense to the damping produced by the load brought about by the cathode ray tube and which must be efiective during the fly-back but prior to the instant when the rectifiers are again out oil.

A decrease in direct voltage may occur owing to the impedance of the rectifiers due to any series resistances included in the rectifying circuit and to any stray inductances; this decrease in voltage can also be obviated, as will be seen hereinafter.

In order that the invention may be more clearly understood and readily carried into effect, it will now be described in greater detail with reference to the accompanying drawing in which:

Figure 1 illustrates one embodiment of a circuit arrangement according to the invention wherein additional damping is supplied,

Figure 2 shows another embodiment of the circuit arrangement according to the invention wherein additional damping is supplied,

Figure 3 illustrates a modification of the circuit arrangement shown in Figure 2 wherein compensation for the decrease in voltage produced by the internal resistance of the rectifier circuit is provided, and

ures 4 and 5 show additional circuit arrangements according to the invention wherein use is made of booster diodes.

Referring now to the drawing and more partlcularly to Fig. 1, the direct voltage is obtained by rectifying the voltage pulses produced across the primary of a transformer I, part of which is included in the anode circuit of a tube 2. A control voltage to be described hereinafter is applied to the controlgrid of this tube. Deflection coils 3 of the cathode ray tube, shown'here as aload resistor Iii, are coupled to the secondary of the transformer, the rectifying circuit being designed as a voltage doubling circuit and comprising rectifiers a and 5, capacitors 5, J and i! and a resistance 9. well known and is not material to :an understandin of the present invention, sortha't a detailed description thereof is omitted.

The load presented by the cathode ray=tube is represented for the sake of simplicity as a variable resistance Ml. A potentiometer across the load circuit and servesxasaisourcefor a control voltage which varies with the load L and is developed across a capacitor 12. This control voltage is fed, via a resistance I3, to the control grid of the right hand-discharge'path of a double triode 14.

A saw tooth voltage as .shown at E9 "is supplied, via input terminals I5, 16 and :a capacitor n, to the control grid of the left hand discharge path and alsoto the control grid-o'f'the right hand discharge path, since these :control grids are interconnected through a capacity 18.

' In this .case the .saw'tooth voltage shown :may be providedin knownmarmerwith negative going voltage pulses '29. The left hand triode part is connected as a cathode follower and .for this :pur-

pose the'cathode .21 is :connectedto:ground potential through a resistance 22. A bias voltage "taken from .a potentiometer .24 -.is applied "to the control grid of the left :hand'portion "through a resistance :23.

The voltageacross the cathode resistanceiZZis applied to .the control grid .;of the .tube 2 through a capacitor.

A bias yo'ltage taken from a :resistance '16 is tied ate the LCBIlIhOdE 215 of the right hand itriode portion. As a result, this TtfiOdB portion :is .only conductive when a voltage of sufiicient value is -operative:across the control grid and-this can only .occur'in the event of .a control voltage :and jnence of a load on the rectifyingeircuit.

"If the right handtriode portion is :opened, cooperation of the control voltage and the 'voltage' 11% causes the oscillatory circuit included .in the anode circuit to be excited when the tubeis .again out ofi. The natural ffrequency of this oscillatory circuit is chosen to exceed the :fre- 'quency of the oscillation occurring across the transformer l during thetfly backythat is 'to say to :be at least about'twice "that "frequency.

"The "voltage :pulse then produced across the anode of the right hand triode portion produces, through a 173132811101 28.211 increase .in the volt- .age across the resistances 29 and .22, theincrease across the resistance 22 being applied to the con- .trol grid of the tube 2.. This tube was already out 'otflbutit is now .re-openedifor a short period, so that additional damping of the yoltage pulses across the primary :0f the transformer 1 is obtained.

.-By a suitable choice-of the value of the control voltage taken from the potentiometer I I, by the adjustment of the right hand 'triode portion and of the tube 2, and, moreover,.by .the'choice of the frequency .of the circuit .2] and the additional control voltage taken therefrom, boththe instant of occurrence and the value of the additional damping can be controlled.

The operation of this circuit is H is coupled 7 the "capacitor 3?.

this 31106.8.

the saw tooth voltage 30 is applied to the control grid of a discharge tube 3| connected as a cathode follower. The signal occurring across a cathode resistance 32 is fed to the control grid of a tube 33.

output circuit of this tube lagain comprises part of the primary of 'a transformer 34, to the secondary of which the deflection coils 35 are connected.

The rectifying circuit is, in this case, of simple construction and-comprises a diode 36 and a capacit-or The cathode ray tube, which in this embodiment .is .also' represented by a variable load resistance it, is connected in parallel with this capacitor.

A "control :voltage varying with this variable lead is taken froma capacitor 39, which is con- :nectedjn series with a resistance ll] in parallel with the series combination of the diode 56 and This control voltage is fed to a potentiometer circuit 4|, 42. A positive bias voltage is fed through arcsistence-QS to the-point Uf=lGDI1II8Bi7iOI1-Of resistances i! and Since "the point of connection isconnected to the anode M .'.of :a diode .proyided in the tube .3 l, the said :biaswoltageserves :as the anode supply source for .The anode circuit .of the diode further comprises ;a capacitor 45, if necessary, in

series with an inductance Mi.

If no control voltage is supplied, the capacitor 2E5, .if the :diode is not conductive, is included in a charging circuit comprising the resistance 43 :and the supply source connected thereto. If :the control voltage :36 is operative across the control :grid of the triode portion of the tube 31, the potential of the cathode of the tube increases durz-ing'tthe stroke of the control voltage and, consequently, "the :diode remains non-conductive.

.During the fly-back of the control voltage, the potential of the cathode drops .until it :reaches fthep'otential oftheanode 144 "of the diode, so that thalatteribecomes conductive and the capacitor i5 becomes discharged :across the diode, the re sistzmce 32 and the inductance 45. As .a result 'iiieipotential nfithe icatho de temporarily; increases. If the control voltage occurring during the fly-back is taken from the capacitor '39, the poof the anode M and hence the instant when the rditodebecomes conductive :are thus controlled, as is also the value of the current then occurring. The extent of the control may be adjusted by the choice :of the values of the resistances 41!, :42 and .3.

Elle voltage across the resistance 32 controls the command of thetube 3-3, which consequently becomes again temporarily conducting during the "fly-back, but prior to the cutting ofi of the rectiher .36., which results :in the desired additional damping of the oscillationacross the primary of the transformer 3 Both in the circuit-arrangement shown in Fig. 1 and in that shown in Fig. 2 the additional damping may be controlled so that with full loading of the rectifying circuit the load of the additional damping is precisely zero, whereas with zero load of the rectifying circuit the load due to the additional damping is precisely similar to the full load liable to occur in the rectifying .circuit. Thedefiection current across the deflection coil of .thecathode ray tube is thennot impaired'by the variable load of the rectifying circui-tdueto the .cathode .ray tube. However, the direct voltage obtained will then be substantially constant only if the rectifying circuit itself does In the -.circuitarran ement shown in Fig. 72, :not exhibit additional losses due to the resistance of the rectifiers, any series resistances and stray inductances.

When the rectifying circuit exhibits additional losses, the direct voltage will still vary when the beam current strength in the cathode ray tube varies, although to a materially smaller extent than in the absence of control.

If this voltage variation is to be avoided, the control described above may be intensified. However, the quantity of energy after the first half period of the oscillation does not remain constant during the fly-back of the saw tooth current, but will increase when the load of the rectifying circuit increases, so that the amplitude of the deflection current increases. This increase in deflection current is undesirable.

Circuit-arrangements with which not only a constant deflection current but also a direct voltage source having substantially no impedance are obtained are described with reference to Figs. 3, 4 and 5.

It may furthermore be observed that the circuit arrangements shown in, say, Figs. 1 and 2 enable a direct voltage source of low impedance to be obtained with normal control, provided that use is made of half wave rectification and, in certain cases, of not more than full wave rectification. Particularly in the case of multiple rectification, or if stringent requirements are to be fulfilled, the impedance occurring will be found to be a source of trouble.

The circuit-arrangement shown in Fig. 3 is based on recognition of the fact that after the use of an additional damping of the kind described with reference to Figs. 1 and 2, but designed so as to be more intense, in order to reduce the impedance of the direct voltage source to zero, the resultant energy difierence must be compensated by a second damping mechanism, before the residual energy is usefully employed for the saw tooth current.

Energy is then withdrawn from the voltage pulses in three ways; first by the load of the cathode ray tube a quantity a, second by the damping described above a quantity 1), and third by the damping to be described hereinafter a quantity 0. These quantities are variable and their variations Aa, Ab and Ac must comply with the relationship Aa+Ab+Ac=0.

The discharge tube which brings about the damping must be controlled in a manner such that, with an increase in the load a, the load b decreases to a greater extent than the extent to which (1 increases. In this case the losses in the rectifying circuit do not result in a voltage variation when the load 0 increases.

This may be realized by supplying to the control grid of the said damping tube a voltage pulse which has a controllable phase shift relative to the pulse from which the direct voltage is taken and the amplitude of which is also controlled.

In the circuit-arrangement shown in Fig. 3 use is made of a solution according to which two voltage pulses are fed to the control grid of the damping tube, the first voltage pulse occurring during the fiy-back, but before the cutting oif of the rectifiers, similarly to the circuit arrangements shown in Figs. 1 and 2, the second voltage pulse also occurring during the fly-back, but after the cutting off of the rectifiers.

In the circuit-arrangement shown in Fig. 3, the first-mentioned pulse is obtained in a manner similar to that of the circuit arrangement shown in Fig. 2 and the corresponding elements of the circuit-arrangements are referred to by identical reference numerals.

As is described with reference to Fig. 2, the resistance 32 in the cathode lead of the tube 3| has produced across it a voltage pulse, by which the tube 33 is opened during the fly-back, but before the diode 36 is cut oil.

From this pulse a pulse of the same polarity but of suflicient timelag can be derived through a potentiometer comprising resistance 32 by supplying the pulse to the control grid of the tube 41.

The anode circuit of this tube comprises an inductance 48,. a tapping of which is connected to the anode supply source. A capacitor 50 is connected between this tapping and the other end of the coil, which is connected through a capacitor to the control grid of a tube 49. The parallel combination of this capacitor and the coil portion concerned constitutes an oscillatory circuit, which is excited by the current passing through the tube 41. The winding of the two coil portions is chosen to be such that the voltage across the control grid of the tube 49 is in phase opposition to the voltage across the anode of the tube 41.

If the natural frequency of the oscillatory circuit in the anode circuit of the tube 47 is equal to or higher than twice the frequency of the oscillation which, during the fiy-back of the saw tooth current, occurs across the primary of the transformer 34, approximately a complete period of the voltage of double frequency occurs during this fly-back across the control grid of the tube 49. The first half period, which has negative polarity, does not produce any variation in the tube '39, since this tube had already been cut off with the use of a negative bias voltage derived from a potentiometer 5|. The second half period is positive going and will cause the tube to be conductive after the threshold formed by the bias voltage is exceeded. The value of the bias voltage and of the voltage fed to the control grid are such that the tube 49 is not opened until the diode 36 of the rectifying circuit is cut off.

The resistance 32 is also included in the cathode lead of the tube 49, so that across this resistance is now set up a second positive going pulse, which has a. correct time lag relative to the preceding pulse.

These two pulses have the effect of rendering the tube 33 conductive for a short period two times during the fly-back, so that the two desired dampings are obtained.

It may be observed that in the Figs. 1, 2 and 3 the deflection circuits are shown, for the sake of simplicity, without efiiciency diode or booster diode, so that the tubes 2 and 33 must be conductive during the whole stroke of the saw tooth current, which is not necessary with the use of a circuit comprising one of the said diodes.

Consequently, in the circuit arrangements shown, the value and the position of the first pulse which has to render the tube 2 or 33 con ductive for a short period during the fly-back, and also the value and the position of the second pulse in the circuit-arrangement shown in Fig. 3 will diiTer from those which will occur in the familiar circuit-arrangement comprising one of the said diodes. It should furthermore be noted that it is not necessary to combine the pulse voltages produced in the circuit-arrangements shown in Figs. 1, 2 or 3 with the control voltage, but that these voltages may be produced across separate resistances. In this case they may be supplied to polarity separate tubes included inthecircuit-arrangement in a manner suohthat duringthe any-back, apositivevoltagepulseoccurs-acrosstheir anodes. Under the control of the pulse fed to the control grids these tubes become conductive at the correct instant during the fiybacland produce the desired damping. However, the drawing shows circuit-arrangements in which such additional discharge tubes are dispensed with.

In the circuit-arrangements shown in Figs. ,4 anda5, in'which use is made of a booster diode, it is ensured in a different manner that both the direct voltage of the rectify-in circuit -an t amplitude of the deflection current remain constant with varying load.

In this case use isalso madeofdamping during thefly-back of thesaw-toothcurrent,but before the cutting off of the rectifiers, part of the-energy thus withdrawn from the voltage'pulses being,

however, stored and -re-supplied to the circuit.

gereagain the damping higher than would be reuuired for the compensation of the load of the cathode ray tube alone.

In the circuit-arrangement shown in-Fig.-.-e the saw tooth control voltage 52*is appliedto the con trol grid of the discharge tube 53. The anode-circuitof this tube includes part of the primary of a transformer 55.

Deflection coils Fat-are connected to part of the secondary of the transformer.

The end of the primary 5 remote from the anode of the tube 53 is connected not only to a capacitor '5! but also to the cathode of a booster diode 58, the anode of which is connected'to the secondary of the transformer. 'The'seriescornbination of the winding 54 and the capacitor '5'.

furthermore comprises the anodesupply source of 1 the tube 55.

Although the operation of this part of the circuit arrangement is known per se, the following maybe briefly stated on =this1subject.

The booster diode 5% assumes a voltage of such during the stroke-of the sawtooth cur rent through the winding 56, that its anode is positive. Consequently, the diode becomes onductive, so that the capacitor becomes charged with such polarity that the voltage across the capacitor 5'! assists in theefiect of the anode-supply source. This has the advantage that the supply voltage may have a lower value.

As in the other embodiments, a rectifying circuit may be connected to the part 54 of the pri mary winding, or, as is shown, to the total prtmary.

In the present embodiment this circuit coinprises two rectifiers 59 and '68, three capacitors 6i, -52 and -33 and a resistance :Ed. The variable load due to the cathode ray tube is again represented by a variable resistance 65.

Connected in parallel with the series combination of the diode 5i and the capacitor 6| is a potentiometer 6%, which is here otherwise connected in series with the anode supply source.

This potentiometer again supplies a control voltage which isrfed through a resistance 61 to the control grid of a discharge tube es.

The anode of this tube is connected to a point on the secondary of the transformer 55 which assumes a positive voltage during the fiyback, whereas the cathode is connected to the junction .of the winding 56 and the capacitor-57. The capacitor 6% interposed between the control grid and the anode, together with the resistance 61 formspart of adifferentiating network. Capacitor -59 maybe formed in whole or inpart byparas'itic capacity.

if the resistance 65 is very .high at a given instant, so that the rectifying circuit is not loaded, a control voltage does not occur across the control .gridiof the tube 68 during the fly-back. A positive voltage pulse .is derived through the differentiating network .61, 59 from the secondary of the transformer. The tube thus becomes conductive and,.since the voltage across the second.- ary winding and hence across the tube 68 is temporarily very high, a high voltage pulse is pro- ,duced. Consequently, the capacitor 5] becomes charged .to .a. value corresponding with a mean chargingcufrrent of several .milliamperes.

If the rectifying -.cir. cuit is entirely loaded, the control voltages-across the-..po.tentiometer .65 becomes sufficiently high to cut ofi the tube 6.8 during theily-b ack.

. The essentialediiferenoe between the circuitarrangement shown in Fig. 5 and that shown in Fig. :1 consistsdn that .thecontrol voltage derived from the potentiometer 66 is fed directly to the control .grid of the tube .68 and in that the cathode lead of the tube comprises the parallel combination of a resistance 10 and a capacitor 7 i. The time constant of this network is chosen such that the diode-conducts only during the fiy-back and prior to the cutting off of the'diodes of the rectifying circuit. The booster diode 58 is now connected not to the secondary but to the primary of the transformer 55. The discharge tube 68 is, again connected to a point of the secondary of the transformer which exhibits positive voltage during the flybacl. The other end of this winding is connected to the anode supply source.

Both in the circuit arrangement shown in Fig. .4 and in that shown in .Fig. 5 the correct ratio between the energy obtained and the energy resupplied can be controlled by correct choice of the connection of the anode of the tube 68 to a tapping or a through winding of the secondary of the transformer 55.

While the invention has been described in specific-embodiments thereof and in specific uses, it is not-desired that it be limited thereto for obvious modifications thereof will occur to those skilled in the art without departing from the spirit and scope of the invention.

What we claim is:

1. An electrical circuit-arrangement for producing i a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a :fly-back portion, comprising means including an oscillatory output circuit coupled to said deflection coil to produce flow of said saw tooth current through-said deflection coil, means to rectify the voltage developed across said oscillatory output circuit during the fly-back portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said *loaclcircuitprovidingdamping for said oscillatory output circuit inversely proportional to the impedance value of said load circuit, and means coupled to said load circuit to produce additional damping of said oscillatory output circuit during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit.

2.;An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube .a fly-back portion, comprising means including an oscillatory output circuit coupled to said deflection oil to produce flow of said saw tooth current through said deflection coil, means to rectify the voltage developed across said oscillatory output circuit during the fiy-back portion of said saw tooth current flow, a first load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said first load circuit providing damping for said ioscillatory output circuit inversely proportional to the impedance value of said first load circuit, means to derive from said first load circuit a control voltage inversely proportional to the impedance of said first load circuit, a second load circuit coupled to said oscillatory output circuit, and means to apply said control voltage to said second load circuit to produce additional damping of said oscillatory output circuit during a portion of the flow of said fiy-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit.

3. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fly-back portion, comprising means including an oscillatory output circuit coupled to said deflection coil to produce flow of said saw tooth current through said deflection coil, means to rectify the voltage developed across said oscillatory output circuit during the fly-back portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for said oscillatory output circuit inversely proportional to the impedance value of said load circuit, means to derive from said load circuit a control voltage proportional to the impedance value of said load circuit, means to derive from said control voltage a positive voltage pulse during the flow of said fly-back portion of said saw tooth current, an electron discharge tube having an input circuit and having an output circuit coupled to said oscillatory output circuit, and means to apply said positive voltage pulse to the input circuit of said discharge tube thereby to produce additional damping of said oscillatory output circuit during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedanceof said load circuit.

4. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fly-back portion, comprising an electron discharge tube having an input circuit and having an output circuit including said deflection coil, means to apply a saw tooth input voltage to the input circuit of said discharge tube to produce flow of said sawtooth current through said defiection coil, means to rectify the voltage developed across the output circuit of said discharge tube during the fly-bacl: portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for the output circuit of said discharge tube inversely proportional to the,

and means to apply said positive voltage pulse to the input circuit of said discharge tube thereby to produce additional damping of said output circult of said discharge tube during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit.

5. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fly-back. portion, comprising an electron discharge tube having an input circuit and having an output circuit including said deflection coil, a first electron discharge system having cathode, control grid and anode electrodes, an output impedance element connected to the cathode of said first discharge system, means to apply an input saw tooth voltage to the control grid of said first discharge system, means intercoupling the cathode of said first discharge system and the input circuit of said discharge tube thereby to produce flow of said saw tooth current through said deflection coil, means to rectify the voltage developed across the output circuit of said discharge tube during the fly-back portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for the output circuit of said discharge tube proportional to the impedance value of said load circuit, a second normally non-conductive discharge systern having cathode, control grid and anode electrodes, means to derive from said load circuit a control voltage inversely proportional to the im pedance value of said load circuit, means to apply said first input saw tooth voltage to the control grid of said second discharge system, an oscillatory circuit coupled to the anode of said discharge system, capacitive means intercoupling the anode of said second discharge system and the cathode of said first discharge system, means to apply said control voltage to the control grid of said second discharge system to render said second discharge system conductive during a portion of the flow of said fly-back portion of said saw tooth current thereby to produce at the cathode of said first discharge system a positive voltage pulse, and means to apply said positive voltage pulse to the input circuit of said discharge tube thereby to produce additional damping of the output circuit of saiddischarge tube during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit.

6. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth currrent having a rising portion and a fly-back portion, comprising an electron discharge tube having an input circuit and having an output circuit including said deflection coil, a first electron discharge systemhaving cathode, control grid and anode electrodes, means'to ap ply a first saw tooth voltage to the control grid of said first discharge system, an output impedance element connected to said cathode, means intercoupling said cathode and the input circuit of said electron discharge tube to apply a second saw tooth voltage to the input circuit of said electron discharge tube thereby to produce flow of said saw tooth current through said deflection coil, means to rectify the voltage developed across the output circuit of said electron discharge tube during the fly-back portion of said saw tooth cur rent flow, a load circuit having a, variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for the output circuit of said electron discharge tube inversely proportional to the impedance value of said, load circuit, means to derive from said load circuit a control voltage inversely proportional to the impedance value of said load circuit, a second electron discharge system comprising said cathode and an output electrode, a capacitive element coupled to said output electrode, means comprising a resistor coupled to said output electrode to charge said capacitive element, means to apply said control voltage to said output electrode to produce at said cathode a positive voltage pulse during a portion of the flow of said fly-back portion of said saw tooth current, and means to apply said positive Voltage pulse to the input circuit of said electron discharge tube thereby to produce additional damping of the output circuit of said electron discharge tube during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional tothe impedance value of said load circuit.

7. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fly-back portion, comprising an electron discharge tube having an input circuit and having an output circuit including said deflection coil, a first electron discharge system having cathode, control grid and anode electrodes, means to apply a first saw tooth voltage to the control grid of said first discharge system, an output impedance element connected to said cathode, means intercoupling saidcathode and the input circuit of said electron discharge tube to apply a second saw tooth voltage to the input circuit of said electron discharge tube thereby to produce flow of said saw tooth current through said deflection coil, means to rectify the voltage developed across the output circuit of said electron discharge tube k during the fly-bacl; portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for the output circuit of said electron discharge tube inversely proportional to the impedance value of said load circuit, means to derive from said load circuit a control voltage inversely proportional to the impedance value of said load circuit, a second electron discharge system comprising said cathode and an output electrode, a series circuit comprising a capacitive element and an inductive element coupled to said output electrode, means comprising a resistor coupled to said output electrode to charge said capacitive element, means to' apply said control voltage to said output electrode to produce at said cathode a positive voltage pulse during a portion of the flow of said flyback portion of said saw tooth current, and means to apply said positive voltage pulse to the input circuit of said electron discharge tube thereby to produce additional damping of the output Cll-' cuit of said electron discharge tube during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional-to the impedance value of said load circuit.

8. An electrical circuit arrangement for producing in a deflection coilof acathode ray tube a saw tooth current having a rising portion and a fly-back portion, comprising means including an oscillatory output circuit coupled to said d eflection coil to produce flow of said saw tooth current through said deflection coil; rectifying means operative during a portion of the flow of of said fly-back portion of said saw tooth current through said deflection coil and inoperative during the remainder thereof to rectify the voltage developed across said oscillatory output circuit during said portion of the fly-back portion of said saw tooth current flow, a loadcircuit having a variable impedance value and comprising a cathode ray tube coupledto said rectifying means, said load circuit providing damping for said oscillatory output circuit inversely proportional to the impedance value of said load circuit, means coupled to said load circuit to produce first additional damping of said oscillatory output circuit during saidportion of the flow of said fly-backportion of said saw tooth currentthrough said deflection coil, said additional damping being proportional to the impedance value of said load circuit, and means coupled to said load circuit to produce second additional a saw tooth current having a rising portion and a fly-back portion, comprising an electron dis charge tube having an input circuit and" having an output circuit including said deflection coil; a first electron discharge system having cathode, control grid and anode electrodes, means to apply a first saw tooth voltage to the control, grid of said first discharge system, an output imped ance element connected to said cathode, means intercoupling said cathode and the input. circuit of said electron discharge tube to apply a second saw tooth voltage to the input circuit of said electron discharge tube thereby to produce flow of said saw tooth current through said deflection coil, rectifying means operative during a portion of the flow of said fly-back portion, of said saw tooth current through said deflection coil and inoperative during the remainder thereof to rectify the voltage developed across the output circuit of said electron discharge tube during said portion of the fly-bacl: portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for the output circuit of said electron discharge tube inversely proportional to the impedance value ofsaid load circuit, means to derive from said load circuit a control voltage inversely proportional to the impedanoevalue of said load circuit, a second elec tron discharge system comprising said cathode and an output electrode, a series circuit comprising a capacitive element and an inductive element coupled to said output electrode, means comprising a resistor coupled to said output electrode to charge said capacitive element, means to apply said control voltage to said output electrode to produce at said cathode a first positive voltage pulse during said portion of the flow of said fly produce first additional damping of the output circuit of said electron discharge tube during said portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit, delay means to derive from said first positive voltage pulse a second positive voltage pulse during said remainder of the flow of said fly-back portion of said saw tooth current, means to apply said second positive voltage pulse to the input circuit of said electron discharge tube thereby to produce second additional damping of the output circuit of said electron discharge tube during said remainder of the flow of said fiy-baclz portion of said saw tooth current through said deflection coil, said second additional damping being inversely proportional to the impedance value of said load circuit.

10. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fiy-back portion, comprising a first electron discharge tube having an input circuit and having an output circuit including said deflection coil, a first electron discharge system having cathode, control grid and anode electrodes, means to apply a first saw tooth voltage to the control grid of said first discharge system, an output impedance element connected to said cathode, means intercoupling said cathode and the input circuit of said first electron discharge tube to apply a second saw tooth voltage to the input circuit of said first electron discharge tube thereby to produce flow of said saw tooth current through said deflection coil, rectifying means operative during a portion of the flow of said fly-back portion of said saw tooth current through said deflection coil and inoperative during the remainder thereof to rectify the voltage developed across the output circuit of said first electron discharge tube during said portion of the fiy-back portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for the output circuit or" said first electron discharge tube inversely proportional to the impedance value of said load circuit, means to derive from said load circuit a control voltage inversely proportional to the impedance value of said load circuit, a second electron discharge system comprising said cathode and an output electrode, a series circuit comprising a capacitive element and an inductive element coupled to said output electrode, means comprising a resistor coupled to said output electrode to charge said capacitive element, means to apply said control voltage to said output electrode to produce at said cathode a first positive voltage pulse during said portion of the flow of said fly-back portion of said saw tooth current, means to apply said first positive voltage pulse to the input circuit of said first electron discharge tube thereby to produce first additional damping of the output circuit of said electron discharge tube during said portion of the flow of said fly-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit, a second electron discharge tube having an input circuit and having an output circuit including an anode electrode and an oscillatory circuit, means intercoupling said output impedance element and the input circuit of said second electron discharge tube, a third normally non-conductive electron discharge tube having an input circuit and having an output circuit comprising said output impedance element, means to derive a first voltage in phase opposition to the voltage developed at the anode of said second electron discharge tube and to apply said first voltage to the input circuit of said third electron discharge tube to produce a second positive voltage pulse across said output impedance element, and means to apply said second positive voltage pulse to the input circuit of said first electron discharge tube.

11. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fly-back portion, comprising means including an oscillatory output circuit coupled to said deflection coil to produce flow of said saw tooth current through said deflection coil, rectifying means operative during a portion of the flow of said flyback portion of said saw tooth current through said deflection coil and operative during the remainder thereof to rectify the voltage developed across said oscillatory output circuit during said portion of the fly-back portion of said saw tooth current flow, a load circuit having a variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for said oscillatory output circuit inversely proportional to the impedance value of said load circuit, means coupled to said load circuit to produce additional damping of said oscillatory output circuit during said portion of the flow of said fiy-back portion of said saw tooth current through said deflection coil, said additional damping being proportional to the impedance value of said load circuit, storage means to accumulate a portion of the energy drawn from said oscillatory output circuit during said portion of the flow of said fiy-back portion of said saw tooth current, and means to supply said accumulated energy to said oscillatory output circuit.

12. An electrical circuit-arrangement for producing in a deflection coil of a cathode ray tube a saw tooth current having a rising portion and a fiy-back portion, a first electron discharge tube having an input circuit and having an output circuit comprising a portion of the primary winding of a transformer, said transformer having a secondary winding coupled to said deflection coil, means to apply a saw tooth voltage to the input circuit of said first electron discharge tube to produce flow of said saw tooth current through said deflection coil, rectifying means operative during a portion of the flow of said fly-back portion of said sawtooth current through said deflection coil and inoperative during the remainder thereof to rectify the voltage developed across the primary winding of said transformer during said portion of the fly-back portion of said saw tooth current flow, a load circuit having a, variable impedance value and comprising a cathode ray tube coupled to said rectifying means, said load circuit providing damping for said primary Winding inversely proportonal to the impedance value of said load circuit, a capacitive element and a voltage supply source connected in series with said primary winding, a second electron discharge tube having cathode and anode electrodes, means to intercouple the end of said capacitive element remote from said voltage supply source to the oathode of said second electron discharge tube, means 1 intercouple the anodeof said. secondelectron: ischarge tubeand a point of one winding ofisaid' :ansformer torender said second. electron disbarge tube conductive during. therisingportion. f the flow of" said saw tooth: current; a. third. iectron discharge tube having. cathode, control rid and anode electrodes, meanstointereouple aid end of said eapacitiveelement. and the oath.-- de of said third electron discharge tube, means 0 intercouple the anode of said. thirdi electron. .ischarge tube and a point of awindingi of said: ransformer at a positive potential during. the ly-back portion. of said sawtooth current flow,v

aid latter winding being connected to said volt- .gesupply'source, means .toderive from said lead :ircuiti a control: voltage inversely proportional 0-.the. impedance of. said loadioircuit, and means. 0 apply. said control voltage tcthecontrol grid; if said third electron discharge tubetoproduce:

.dditional-damping for saidprimary-winding durngi said portion of thefiow of said" fly-back por ion of said. saw. tooth current through. said-Clea. iection coil, said additional damping. being-pro :ortional. to the impedance value of said; load :ircuit.

12,1111 which a secondcapacitive element is interposed between the anode and control grid electrodes of' the third electron discharge tube and in whiohthe controlvoltage is appliedtothe control grid? of: the third electron discharge: tube through a. resistance element, said. second capacitive element and said resistance element forming a. differentiating network;

14.. A. circuitearrangement as claimedin claim 12, in which aparallel combination of. aresistance elementand a second capacitive element is 0011'- pled to the cathode of; the third electron discharge tube.

JOHAN HAANTJ ES.

J OSUE JEANPHILIPPE VALETON;

BERNARDUS WILLEM VAN INGEN SCHENAUL References Cited in the file oi'this patent UNITED- STATES PATENTS Number; Name Date.

2,521,741 Parker Sept. 12-, 1950 2,543,305 Schwartz Feb. 27, 1951 5 2,5453% Edelsohn Mar. 13, 1951 2,561,817 Parker July, 24, 1951 

